Magnesium chloride is a compound having the chemical abbreviation MgCl2, and exists in its steady state as a liquid. It has a variety of different uses. One of these uses is as a de-icer or anti-icer. In this capacity it is applied as a brine solution directly to a surface to eliminate or prevent ice from forming by lowering the temperature at which the water freezes.
Magnesium chloride is increasingly being applied to roads, streets and highways during winter months to prevent dangerous driving conditions. The process of lowering the freezing point allows snow removal equipment such as snowplows to more effectively remove the soft, slushy material from the surface. It also has been found to be favorable in comparison to sand and salt mixtures which pollute the air and otherwise harm the environment.
As vehicles travel on these routes the magnesium chloride splashes off the surface of the road and deposits on the vehicle. During repeated travel over the winter months, the magnesium chloride continues to build up and can become as much as ½ inch thick in high exposure areas on the vehicle. Unlike other salts applied to the road, magnesium chloride does not dry out, and will retain water and continue to maintain solubility as long as the environment remains above twenty-seven percent (27%) humidity. Magnesium chloride in this state has a corrosive effect on several different types of metal, plastic, rubber, and other surfaces including painted surfaces of the type listed above. This corrosive effect includes deterioration to the strength and durability of the material, and often causes discoloration. In addition, magnesium chloride can deteriorate wiring insulation and cause serious damage to electrical systems. This level of buildup can deteriorate metal structural surfaces of the vehicle and cause electrical systems to malfunction, creating the potential for catastrophic failure for a vehicle traveling at highway speeds. Simply washing or spraying the vehicle with water or soap will not remove the magnesium chloride deposits.
Magnesium chloride contamination on barriers, signs, guardrails, power distribution equipment and other roadside structures is also a serious problem. As the compound is applied to the road surface it can splash onto these structures and cause corrosion. Vehicles traveling on the road, including street sweepers and snowplows may also cause magnesium chloride to become deposited on these structures. Furthermore, the magnesium chloride is able to penetrate the concrete surface of the road and contaminate the reinforcing steel or rebar members, thereby weakening structures such as overpasses, bridges and ramps.
Magnesium chloride contamination caused by pedestrian travel along these roads and subsequent tracking of magnesium chloride into buildings causes yet another problem. Metal decking and other metal floor surfaces may be damaged by the contamination of magnesium chloride. In order to prevent damage to the floor surface expensive cleaning measures must be taken.
Various solutions and methods for treating magnesium chloride deposits have been attempted during recent years. An early solution included a high percentage of hydrofluoric acid. However, this solution had the serious disadvantage of causing corrosion to the surface it was applied to, and to other surrounding surfaces including glass. Further renditions made to this solution reduced but never eliminated harmful environmental effects caused by the concentrated acid present in the solution. Other methods have since been introduced to eliminate these disadvantages.
One of these methods is disclosed in U.S. Pat. No. 5,609,692. This invention relies on a dilute aqueous solution to remove a chloride compound from a metallic, concrete, plastic or plastic laminate surface. One disadvantage of the system disclosed in U.S. Pat. No. 5,609,692 is the number of different agents that must be used in conjunction with the hydroxyacetic acid. These include sodium xylene sulfonate, triethanolamine, diethanolamine and stoichiometric soap. In addition, this invention does not disclose a method for inhibiting chloride compound build up on metallic surfaces in combination with the solution employed.
Other systems have tried to overcome these disadvantages. One such system is disclosed in U.S. Pat. No. 6,544,342. This invention discloses a method for controlling the level of acidity while removing contaminants from a metallic article. However, this method requires the use of an acid bath, which is impractical for use with a vehicle of any size. It is also impractical for use directly on roadside structures.
It is therefore desirable to provide a solution and method for applying the solution to these and other surfaces to remove magnesium chloride and inhibit further corrosion. It is furthermore desirable to provide a solution that is both easy to apply and less damaging to a number of different freestanding structures.